A battery module for use in an electric automobile or hybrid car has a plurality of single batteries arrayed in lines, the single batteries having positive and negative electrode terminals. The plurality of single batteries are connected serially or in parallel by connecting the electrode terminals of adjacent single batteries with a bus bar (connection member) (see Patent Literature 1).
In a bus bar module (battery wiring module) in Patent Literature 1, a bus bar is overlaid on a flat plate-shaped terminal for voltage detection, and a wire connected to the terminal for voltage detection is guided to a battery ECU. Thereby, the bus bar module (battery wiring module) detects whether a voltage of a single cell is kept in a predetermined range on the battery ECU side.